Duplex fusing apparatus and method

ABSTRACT

An improved flash fusing apparatus for fusing toner images onto flexible support material. First and second elongated flash lamps are closely spaced and a flexible support web bearing loose toner images on both sides is advanced along a predetermined cylindrical path encircling each of the flash lamps along its longitudinal axis exposing each side of the web to flash radiation from the lamps.

United States Patent [191 Donnelly et al.

1 1 Nov. 18, 1975 [5 DUPLEX FUSING APPARATUS AND METHOD I [75]Inventors: Thomas L. Donnelly; Edward J.

Mullen, both of Webster, NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: Oct. 18, 1974 [21] Appl. No.: 516,058

[52] US. Cl 219/216 [51] Int. Cl. H05B 1/00 [58] Field of Search219/216, 388;

[56] References Cited UNITED STATES PATENTS Roshon, .lr 219/216 5/1969Michaels 219/388 X 9/1969 Nakamura et al. 219/216 X Primary Examiner-C.L. Albritton ABSTRACT An improved flash fusing apparatus for fusingtoner images onto flexible support material. First and second elongatedflash lamps are closely spaced and a flexible support web bearing loosetoner images on both sides is advanced along a predetermined cylindricalpath encircling each of the flash lamps along its longitudinal axisexposing each side of the web to flash radiation from the lamps.

4 Claims, 1 Drawing Figure us. Patent NOv.18,1975 3,920,952

The invention relates generally to flash fiising and particular to amethod and apparatusfor fusingtoner images onto flexible supportmaterials- More ,speci' fi cally, this invention relates'to axerographicflash fusing apparatus and methods for rapidly andefficiently producing uniform duplex image fixing on each sidesofsupport material. 1%

In the xerographic 'prooess'jsa plate, generally comprising a conductivebackingupon which placed a photoconductive I insulating ysurface, isuniformly charged and the photoconductive surface then exposed to alight image of an original to be reproduced. The photoconductive surfaceis caused to become conductive under the influence of the light imagesoas to selectively dissipate theelectrostatic charge, found thereon toproduce what is developedby means of a variety of pigmented resinmaterials specifically made for this purpose which are known in thexerographic art as toners. The toner material is electrostaticallyattracted to the latent image areas on the plate proportion to thecharge concentration foundthereon fAreas 'tiie flash fusing process, amajor problem with flash fusant energy. Because of the properties ofmost copy materials-as for example, paper, most" of the energy inci-'dent thereon is wastedby being transmitted through the copy or by beingreflected-away from the fusing area. Another disadvantage-associatedwiththe prior art flashfusing apparatus has heretofore been thenonuniformity'of image fixing produced. This phenomena is primarily dueto the fact that it is difficult to produce v highly uniform irradianceon a large receiving surface as for example a sheet of pa'per,from arelatively small source such as a flash lamp. This problem is furtherheightened in the case of duplex images on both sides "Whileconsiderable effort has been expended in pro- "s idings'chemes'forenhancing the efficiency and uniforof high chargevconcentration become areas of high toner density while correspondinglylow charge image areas become proportionally less dense. The developedimage is transferred to a final support material, typically paper, andfixed thereto to form a permanent record or copy of the original.

Many forms of image fixing techniques are known in the prior art, themost prevalent of which are vapor fixing, heat fixing, pressure fixingor a combination thereof as described in US. Pat. No. 3,539,161. Each ofthese techniques, by itself or in combination suffer,

efficiency, and ease of control. A further problem associated with heatfusers has been their tendency to burn or scorch the support material.Pressure fixing methods, whether hot or cold have created problems withimage offsetting, resolution degradation and producing consistently agood class of fix. On the other hand, vapor fixing, which typicallyemploys a toxic solvent has proven commercially unfeasible because ofthe health hazard involved.' Equipment to sufficiently isolate .thefuser from the surrounding ambient air must by its very nature becomplex and costly.

With the advent of new materials and new xerographic processingtechniques, it is now feasible to construct automatic xerographicreproducing apparatus capable of producing copy at an extremely rapidrate. Radiant flash fusing is one practical method of image fixing thatwill lend itself readily to use in a high speed automatic process asdescribed in US. Pat. No. 3,529,129. The main advantage of the flashfuser over the other known methods is that the energy, which ispropagated in the form of electromagnetic waves, is instantaneouslyavailable and requires no intervening medium for its propagation. As canbe seen, such apparatus does not require long warm-up periods nor doesthe energy have to be transferred through a relatively slow conductiveor convective heat transfer mechamsm.

Although an extremely rapid transfer of energy between the source andthe receiving body is afforded by mity of fix of electrographic flashfusing systems, most efforts have been-directed toward the provision ofspecially contoured reflecting surfaces which are designed to at leastpartially surround the flash lamp and thereby conserve energy viamultiple reflections as set forth in US. Pat. No. 3,529,129. In additionto being costly to fabricate, such reflecting surfaces tend to becomecontaminated by loose toner particles and thereby necessitate frequentcleaning operations.

It is therefore an object of this invention to improve flash fusing ofxerographic toner images on support material.

Another object of the invention is to accomplish flash fusing of eithersimplex or duplex electrostatic images with a single flash for apredetermined area.

Another object of the invention is to enable highly efficient fusing oftoner images onto flexible support material.

Still another object of the invention is to fuse loose toner images onboth sides of a support material simultaneously.

For a better understanding of the invention as well as other objects andfurther features thereof, reference is had to the following descriptionwherein the FIGURE is a side view of a web of support material bearingxerographic toner images on each side thereof for fusing according tothe present invention.

Referring now to the Figure in accordance with the present invention,loose image toner particles 10 and 11 deposited onto a flexible supportweb 12 at developer stations 14 and 15 respectively, are fusedsimultaneously. Web 12 is transported about the axes of elongatedsources of radiant energy in the form of flash lamps 16 and 18. The webis advanced along the curved path of a guide track 20 by a driven roller22 which is rotated in a direction indicated by the arrow. It will beappreciated that images 10 and 11 are moved along a circular path ineach fusing zone such that the toner images are untouched andcontinuously face toward the center of curvature of the path where flashfusing' lamps l6 and 18 are situated. It will be further appreciatedthat each of the flash fusing lamp fusing zones has a configurationwhich is circular or cylindrical such that uniform irradiance is insuredto all points on the cylindrical surface from the particular flash lamppositioned along the central axis thereof. In this manner, it is notnecessary to fuse the images onto a support material in piece mealfashion by energizing the lamp a number ofvery good toner fusion. Pulsedurations between 0.25

and 1.5 milliseconds were found to provide acceptable fusing with pulsesbetween 0.5 and 1.2 milliseconds giving better fusing results. It hasalso been found that longer pulses of energy are required as the powerlevel increases.

The efficiency of the duplex fusing system of the above-describedinvention can reduce the power required to fuse ordinary simplex copiesby as much as 50 percent. It is believed that this is because of theunique configuration of the path through which the copy web is advancedpast the flash fusing lamps. It will be further appreciated that theimproved flash fusing system will provide improved efficiency even whereimages are on a single side of theweb material.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in the artwithout departing from the spirit of the invention.

What is claimed is:

1. An improved flash fusing apparatus for fusing toner images ontoflexible support material comprising a first elongated flash lamp,

a second elongated flash lamp positioned closely adjacent to said firstlamp, and

means for advancing flexible support material bearing loose toner imagesalong a predetermined path substantially encircling each of said firstand second flash lamps along their longitudinal axes thereof to fuse thetoner images thereto. 2. Apparatus according to claim 1 wherein saidflexible support material is in the form of a web.

3.,Apparatus according to claim 2 wherein the loose toner images are'oneach side of the web.

4. Apparatus according to claim 2 wherein track means guide theweb alongits predetermined path.

1. An improved flash fusing apparatus for fusing toner images ontoflexible support material comprising a first elongated flash lamp, asecond elongated flash lamp positioned closely adjacent to said firstlamp, and means for advancing flexible support material bearing loosetoner images along a predetermined path substantially encircling each ofsaid first and second flash lamps along their longitudinal axes thereofto fuse the toner images thereto.
 2. Apparatus according to claim 1wherein said flexible support material is in the form of a web. 3.Apparatus according to claim 2 wherein the loose toner images are oneach side of the web.
 4. Apparatus according to claim 2 wherein trackmeans guide the web along its predetermined path.